As technology improves, users demand smaller devices that are mobile, have more memory, and can execute more complex functions. As one example, notebook computers are much smaller than their desktop counterparts, but have comparable memory and execute the same applications.
As another example, mobile telephones use modern communications techniques to allow the user to make and receive calls from just about anywhere. Most mobile phones include a database of names and numbers to make dialing easier.
Personal digital assistants (PDAs) are an extension of notebook computers, are typically small enough to fit in someone's hand, and operate via a small touch screen. PDAs also have databases (such as an address book and a compilation of email messages) to assist the operator in performing operations.
These devices have at least two features in common. First, they all have databases and applications (executable programs). Second, they all are portable. This portability allows any of these devices to be used in many environments. Examples of environments include the user's home, the user's office, and the home or office of another person.
Since these types of devices can be linked to multiple environments, a problem may arise in the unwanted sharing of data or applications. As an example, suppose a user uses his notebook computer for home accounting purposes while at home and for the generation of work product (e.g., proposals or budgets) while at work. When the notebook computer is in the work environment, other people may be able to obtain access to the user's home accounting data. Similarly, work product may become available to the user's family members when the notebook computer is used at home.
Currently, some operating systems, such as Windows® 95, 98, 2000 and NT from Microsoft, allow a user to grant access to a directory, file or application on an individual or group basis. In the Windows® operating systems, the user uses the Control Panel to grant other users read only, write only or read/write access. The access that the third party users receive is assigned to each directory, file or application. It is up to the user to get the network user names of everyone who will receive access to every directory, folder or file.
Like reference symbols in the various drawings indicate like elements.